1. Technical Field
The present invention relates to an energy degrader to attenuate the energy of charged particles and a charged particle irradiation system including the same.
2. Description of the Related Art
Equipment that irradiates a patient with charged particles, such as proton beams, to perform cancer treatment is known. This kind of equipment includes a cyclotron to accelerate ions (charged particles) generated by an ion source, a transport line to transport the charged particles accelerated by the cyclotron, and a rotatable irradiation device (rotating gantry) to irradiate the patient with charged particles from an arbitrary direction.
In a particle beam irradiation device disclosed in the related art, a depth-direction position of the charged particle beam that reaches the inside of an irradiation object is controlled by attenuating the energy of the charged particle beam accelerated by a synchrotron (accelerator) using a range shifter. This range shifter is formed so as to have a thickness changing in a stepwise manner, and controls the position in a depth direction by making the charged particle beam pass through a specific stage of the stages formed in a stepwise manner.
In the technique disclosed in the related art, the attenuation of energy is changed by changing the passing position of the charged particle beam by driving the range shifter in one axial direction.